A huge £6.2 billion mega-project is underway to build the world’s longest underwater rail and road tunnel.

The immense tunnel is expected to be open in 2029 connecting Scandinavia and Central Europe under the Baltic Sea and slashing travel times between the two regions.

The Fehmarn Belt tunnel, or the Fehmarn Belt fixed link, is an 11.1-mile (18-kilometre) long immersed tunnel located 40 metres beneath the Baltic Sea connecting the Danish island of Lolland with the German island of Fehmarn.

It is set to cut travel times between this part of Denmark and northern Germany to as little as seven minutes.

Once completed, the Fehmarnbelt Tunnel will be the world’s longest immersed tunnel, making it the largest ongoing infrastructure project in Northern Europe.

The Danish town of Rødbyhavn and the German town of Puttgarden are only 11 miles apart, however, getting between the two currently involves a 45-minute ferry journey.

But under the water, the construction of the Fehmarnbelt tunnel is well underway which will eventually allow for travel between these two regions to be done in as little as seven minutes by train or 10 minutes by car. 

This impressive tunnel’s first element was inaugurated by the Danish King Frederik X in June who unveiled a plaque at the entrance of the tunnel’s first 217-metre section.

Initially the project was estimated to cost over £4.6 billion but that figure quickly rose to £6.2 billion with the tunnel being financed by Denmark with a toll being collected by passengers from the crossing. 

Upon completion, goods will be able to be transported by rail, including steel, from as far north of Norway to southern and central Europe.

Alongside moving goods, journey times for the surrounding areas will be slashed including travel time between Copenhagen and Hamburg from 4.5 hours to 2.5 hours.

The tunnel, which is being built by Sund & Baelt, will also replace the current heavily-travelled ferry service which is being operated by Scandlines. 

This means vehicles will be able to cross the Baltic Sea over four lanes in as little as 11 minutes 

CEO of Sund and Baelt, Mikkel Hemmingsen said: “It’s part of this link which Europe is trying to make between northern Norway and southern Europe, which started when we built the Øresund bridge between Copenhagen and Malmö. 

“To finish the link, we have to build this connection.”

In order for the tunnel to minimise environmental issues, sections of the Fehmarnbelt are being built above the ground submerged on to the sea floor which Hemmingsen said will allow for more efficiency and will be better for the environment. 

Construction of the tunnel on the Danish side began in 2020 with the German side’s construction beginning in the spring of 2021. 

The Fehmarnbelt link will be user-financed with eventual revenue being used to repay the loans raised to finance the construction.